RIO DE JANEIRO – The Brazilian armed forces have begun patrolling the streets of Rio de Janeiro, which in August will host the Olympic Games.

Army, navy and air force troops since midnight Sunday have been providing extra security at some of the key sites in the city, including train stations, water distribution centers and electricity and nuclear power facilities.

The operation marks the start of Defense Ministry activities during the Olympics Games, which will commence on Aug. 5 amid fears of a terrorist attack.

To guarantee security, the Brazilian military will deploy 12 vessels, more than 1,600 vehicles, 70 armored cars, 28 helicopters, about 50 small or medium boats and 174 motorcycles.

Brazilian authorities strengthened security after tensions rose over possible terrorist attacks by “lone wolves” during the competition, to be attended by at least 45 heads of state and government.

Foreign Minister Jose Serra said on Saturday that no country is “immune” to terrorist attacks, which have increased in number in recent weeks in several parts of the world.

The Sao Paulo daily O Estado reported Sunday that at least 50,000 tickets for the Games were returned to purchasers after Brazil increased its alert level amid fears of a potential attack.

Last week, 11 people were arrested in Brazil for allegedly planning to stage an attack during the Games and they are currently being held in a maximum security prison.

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